// Copyright 2012 The Go Authors.  All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// +build helenos

package exec

import (
	"errors"
	"os"
	"strings"
	"syscall"
)

var ErrNotFound = errors.New("executable file not found in /app")

func findExecutable(file string) error {
	d, err := os.Stat(file)
	if err != nil {
		return err
	}
	if m := d.Mode(); m.IsDir() {
		return syscall.EISDIR
	}
	return nil
}

// LookPath searches for an executable binary named file
// in the /app directory.
// If file begins with "/", "./", or "../", it is tried
// directly and the path is not consulted.
func LookPath(file string) (string, error) {
	// skip the path lookup for these prefixes
	skip := []string{"/", "./", "../"}

	for _, p := range skip {
		if strings.HasPrefix(file, p) {
			err := findExecutable(file)
			if err == nil {
				return file, nil
			}
			return "", &Error{file, err}
		}
	}

	path := "/app/" + file
	
	if err := findExecutable(path); err == nil {
		return path, nil
	}
	return "", &Error{file, ErrNotFound}
}

